The invention discloses a sulfide inhibitor for treating aging oil. The sulfide inhibitor used for the dehydration of the aging oil in oil fields is characterized in that the inhibitor comprises the raw materials with the following weight percentage of 15.2-26.0 percent of water solution with 0.05 percent of polypeptide coupling reagent (HATU)C10H15F6N6OP, 4.0-6.5 percent of sodium nitrite, 2.0-3.5 percent of sodium sulfate, 3.0-6.5 percent of sodium lactate, 0.05-0.1 percent of Vitamin C and the rest is water. The sulfide inhibitor has the effects of ensuring both the stable operation of the aging oil entering the electric dehydration and the quality of separated sewage when adding to 50mg/l-100mg/l during the treatment process of the aging oil.